The present invention relates to an improved means for making an envelope and, more particularly, to an improved means of sealing the open edges of an envelope blank while folding it around an insert to form a mailable letter.
The invention is adapted for rapid application and precision control of the volume and pattern of the adhesive to assure quick sealing of the envelope. The present system is particularly adapted to be used with a roller folding machine to create a mailing piece in one single passage. In addition, the present invention is adapted to insure that the nozzles for applying glue to the glue flap of the envelope (or to any other piece of paper) remain in a clean and usable condition so that they may be used immediately when they are needed.
The present state of art consists of a variety of methods for depositing an adhesive bead directly onto the paper. This requires extremely precise timing to avoid the possibility of squirting the adhesive bead into and onto unwanted areas. Those systems require comparatively low paper speed and have inherent clean-up problems. In high speed production of envelopes, glue nozzles are used to glue the envelope seal flap panel and the various other panels together. It is important that the glue nozzles be available to apply glue the instant that the glue is needed. Hence, if for some reason the glue nozzles remain inactive or in a deactivated condition for a period of time, glue in the glue nozzle may harden so that the glue is not available immediately when it is needed. This creates lost time which is counterproductive to modern high speed envelope forming methods.
In general, the system consists of a pressurized and controlled adhesive distribution system. In accordance with the present invention, an envelope is formed from a blank sheet of paper having a center panel, a front panel, a rear panel. It may also have a separate seal flap panel attached to the front panel. The panels are adapted to be folded relative to each other to form the envelope. The edges of the envelope are adhered together and the front panel is adhered to the previously-folded rear panel in order to complete the security of the envelope. If a seal flap is present, the seal flap is folded over and adhered to the previously folded center panel. The sheet of paper is first moved beneath an adhesive-depositing mechanism which deposits adhesive onto opposed side edges of the blank sheet. Another adhesive-depositing mechanism deposits spots of adhesive onto the inner surface of the last panel to be folded (whether it be the front panel or the seal flap panel). The envelope is then moved back into a folding mechanism which first folds the various panels relative to each other to permit the side edges of the panels to be adhered together and the last panel to be folded to be adhered to a previously folded panel.
Spaced nozzles (preferably seven) are provided to deposit shaped beads of adhesive onto the inner face of the last panel to be folded. A series of defector ramps are positioned below a glue manifold and its glue applicator nozzles. As the front edge of the sheet of paper to be sealed passes below the row of nozzles (with a measured charge or bubble of adhesive formed from and suspended on each tip), it encounters the series of deflector rams which deflect it upward. The front edge also strikes a front folder plate stop which forces the paper to bow or buckle upwardly and into contact with the adhesive droplets or charges on the nozzle tips so that they are deposited onto the paper surface. The paper is then retracted back and away from the front folder plate stop which causes the bow or buckle to disappear and causes the paper to drop away from the nozzles leaving the droplets firmly deposited on the surface inwardly spaced from the front edge thereof.
In addition, the present invention keeps the glue in the nozzles in a moist soft and usable condition during the time where the nozzles are inactive or in a deactivated condition so as to prevent it from hardening and keep it in condition for immediate deposition on the seal flap panel when the nozzles are reactivated. This may be accomplished by placing the nozzles in an environment which prevents air from accessing the nozzle tips and drying the adhesive (preferably a moist environment) for the length of time that the nozzles are inactive (in a deactivated state) and are not feeding glue. This prevents the glue at the tip of the nozzles from hardening.
The present invention produces an inexpensive generated piece of mail produced at a very high speed on a system specifically designed to convert one sheet of paper into a sealed, letter-like piece of mail acceptable by and meeting post office regulations.